Volume control system



1937. e. P. ADAlR ,09

VOLUME CONTROL SYS TEM Original Filed July 3. 1931 6150/?615 P A DA Patented Oct. 12, 1937 UNITED STATES PATENT OFFICE Original application July 3, 1931, Serial No. 548,695. Patent No. 2,010,002, dated August 6,

1935. 1935, Serial N0. 28,499

2 Claims.

Divided and this application June 26,

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) My invention relates broadly to volume control systems and more particularly to a circuit arrangement for automatically controlling the coupling of the eiectrical circuits in a radio receiv- 5 ing system for correspondingly controlling the volume of the reproduced sound.

This application is a division of my application Serial No. 548,695, filed July 3, 1931, for Volume control system, which has matured into Patent Number 2,010,002.

One of the objects of my invention is to provide a circuit arrangement for reducing fading effects in radio broadcast receiving circuits by automatically controlling the coupling of the circuits in the receiver in accordance with the amplitude of the incoming signaling energy.

Another object of my invention is to provide a volume control circuit for radio broadcast receivers which operates independent of frequency for maintaining the volume of sound reproduced by the radio broadcast receiver constant independent of fading eiiects.

Still another object of my invention is to provide a construction of mechanical actuator for controlling the volume of reproduced sound in accordance with variable conditions of fading in the circuits of the radio broadcast receiver wherein the parts are arranged to avoid appreciable wear and to give gradual control over the entire range of the receiving apparatus.

A further object of my invention is to provide an arrangement of variable inductance device automatically operative according to the character of the received signaling energy for controlling the transfer of the signaling energy from one circuit to another.

Other and further objects of my invention reside in the circuit arrangement for and the construction of the variable coupling device used in 40 association with the amplifier circuits of a radio broadcast receiver as set forth more fully in the specification hereinafter following by reference to the accompanying drawing, which shows an arrangement of automatic coupling control ap- 45 paratus in Which the inductive association of the coupling coils in an amplifier system is variably controlled in accordance with the amplitude of the incoming signaling energy, in accordance With my invention.

The volume control system of my invention is adaptable for installation in existing types of radio broadcast receivers. The coupling control mechanism may be assembled as a separate unit and incorporated in existing equipment at very reasonable cost. The control circuit of my invention may be built into the radio receiving apparatus during the usual production thereof at very reasonable cost. The control mechanism of my invention comprises a, variable impedance device, the effective value of which is electromagnetically controlled in accordance with the amplitude of the incoming signaling energy. The operation of the variable impedance device is so damped that there is no tendency toward amplitude distortion. The effective variation in impedance may be made as fast as desired to meet special conditions. I may arrange the variable impedance device intermediate the stages of amplification or the variable impedance devices may be arranged between the antenna and the amplification circuit of the receiver, or between the amplifier system and the sound reproducing circuit.

In applying the volume control system of my invention to existing types of receiving circuits, all voltages and currents of the high frequency cascade circuit remain unchanged so that they may be adjusted for maximum efficiency thereby reducing to a minimum signal distortion and so called cross-modulation due to improper adjustment of tube voltages which is inherent in voltage changing control circuits. In applying the variable impedance system of my invention to existing receiving circuits there is no tendency for the receiving circuit or amplifier to 0scillate or flutter as is the case with other systerns of volume control. The system of my invention provides automatic control over a much wider range of signal strength than has been possible with previous volume control systems. The volume control device of my invention operates independent of frequency of the actuating signal.

Referring to the drawing in detail the variable impedance coupling device is shown enclosed 40 within the dotted line I4. The device comprises an electromagnetic winding I! mounted on a movable armature H5. The armature I6 is pivotally mounted for rotary movement between the r magnetic pole pieces of the magnetic field system l5. Movable armature 16 carries the pointer or indicator I8 which is normally biased by means of spiral spring 19 to occupy the central position with respect to the scale 20, as shown in the drawing. The shaft 66 carries variometer wind- 0 ings 69 which are inductively related to the inductance 15. The shaft 61 carries variometer windings l0, likewise inductively coupled to the inductance l5. Shafts 61 and 66 and the indicator [8 are mechanically coupled one to another and 68.

The variable impedance coupling device enclosed within the dotted line i4 is connected in circuit between the high frequency amplifier tube 2 and the high frequency rectifier tube 3; Control tube 4 is provided to actuatelthe variable coupling device.

The input circuit 5 of high frequency amplifier tube 2 is completed from the ground l2 through suitable potential source 64 for supplying predetermined bias potential on the grid 20 of tube 2. Cathode 2a of the tube 2 is shown connected to ground. The terminals to the input circuit are shown at! connected through condenser i3 to selectively tuned circuit 5. The output circuit of tube 2 connects from'anode 2d to the control rid to in the input circuit of control tube 4 through condenser H The control tube 6 has the grid electrode 30 thereof biased from suitable potential source 65 through resistor H. The input circuit of tube 4 is completed to ground l2 and cathode ca. Anode id in the output circuit of control tube l connects through winding ll of the magnetic actuator to the source of anode potential.

Variometer windings 69 which are inductively related to the inductance T5 are connected in the output of the high frequency amplifier tube 2, including the anode 2d and the resistance 8 leading to the source of anode potential. A control circuit including shunt connected impedance ll connects across the windings m for efiecting adjustment of and compensating for changes in, inductance in the coupling system. The inductance I5 is connected to the grid 3c and the cathode 3min the input circuit of the high frequency rectifier tube 3. Condenser i8 is employed to tune inductance 15. By varying the spacial relation of the sets of inductances 69 and ill with ance with'the intensity of the received signal.

As the current in the plate circuit of control tube Li increases, the coupling between inductances t3 and Iii and inductance 15 is decreased, thereby maintaining the output current at'terminals Q8 substantially constant.

In order to furnish the required operating potentials on the anode 3d of the rectifier tube 3, I provide the resistance element 33 as shown. I also arrange suitable capacities 29 and 45 as shown to improve the operation of the system.

The anode potential for tubes 3 and t is supplied at terminals 35.

. The control system is. provided with all required electrical shielding in order to avoid undesired interference with the operation of the circuits.

factured and used by and for the Government of the United States of America, for governmental purposes, without the payment'of any royalties thereon.

What I claim as new and desire to secure by Letters Patent of the United States is as follows;

1. An automatic volume control system including a Volume control device comprising an electromagnetic actuating device including a field magnet and an armature carrying an actuating Winding, an electrically insulated shaft connected with said armature, an indicator connected with :said shaft and operating over a calibrated scale,

an inductance device mountedon said shaft, a stationary inductance device disposed in coupling arrangement with the said inductance device,

said inductance devices constituting coupling means in an electron tube system, the coupling between said inductance devices being variable under the control of said electromagnetic actuating device, and a compensating device insulatingly connected to said shaft, said compensating device comprising a pair of spacially related coils shunted by a variable impedance and inductively related to said stationary inductance device,

2. An automatic volume control system including a volume control device comprising an electromagnetic actuating device including a field magnet and an armature carrying an actuating V winding, an electrically insulated shaft connected with'said armature, an indicator connected with said shaft and operative over a calibrated scale, an inductance device mounted on said shaft, a stationary inductance device disposed in coupling arrangement with the said inductance device, said inductance devices constituting coupling means in an electron tube system, the coupling between said inductance devices being variable under the control of said electromagnetic actuating device, a compensating inductance device mounted on said shaft remote from the connection of said shaft with said armature and in coupled relation with said stationary inductance device, and a variable impedance device connected in shunt with said compensating induc tance device.

GEORGE P. ADAIR. 

